South Korea's new president on Monday promised a strong military response to any North Korean provocation after Pyongyang announced that the two countries were now in a state of war.
President Park Geun-Hye's warning came as North Korea's rubber-stamp parliament was set to hold its annual session and a day after ruling party leaders vowed to enshrine Pyongyang's right to nuclear weapons in law.
In a meeting with senior military officials and defence minister Kim Kwan-Jin, Park said she took the near-daily stream of bellicose threats emanating from the North over the past month "very seriously."
"I believe that we should make a strong and immediate retaliation without any other political considerations if (the North) stages any provocation against our people," she said.
Park, a conservative who had advocated cautious engagement with the North during her campaign, has been compelled to take a more hardline posture after assuming office in February.
The Korean peninsula has been caught in a cycle of escalating tensions since North Korea's long-range rocket launch in December which its critics condemned as a ballistic missile test.
United Nations sanctions were followed by a nuclear test in February, after which came more sanctions and more apocalyptic threats from Pyongyang as South Korea and the United States conducted joint military drills.
Those threats have run the gamut from limited artillery bombardments to pre-emptive nuclear strikes, and have been met with warnings from Seoul and Washington of severe repercussions.
The US military said on Monday it had deployed F-22 Raptor stealth fighters to South Korea as part of the ongoing "Foal Eagle" military exercise. The jets were reportedly flown out of the US air base in Okinawa, Japan.
North Korea has already threatened to strike the US mainland and US bases in the Pacific in response to the participation of nuclear-capable US B-52 and B-2 stealth bombers in this year's exercise.
The annual gathering of the North's Supreme People's Assembly usually scores low on important policy announcements - its role largely limited to unanimously pushing through pre-decided budgets and personnel changes.
But with North Korea having declared itself in a "state of war" with the South, Monday's session will be closely watched for any sign of the current crisis impacting on the fortunes of members of the ruling elite.